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Electronic Supporting Information

A Delayed Curing ROMP Based Thermosetting Resin

Ryan Baumgartner,a Konrad Ryba,b Ziyuan Song,b Ruibo Wang,b Keith Harris,c Joshua S. Katz,d

and Jianjun Cheng*,a,b

a Department of Chemistry and b Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. c Formulation Science, Corporate Research and Development, The Dow Chemical Company, Midland, Michigan 48667, USA. d Formulation Science, Corporate Research and Development, The Dow Chemical Company, Collegeville, Pennsylvania 19426, USA.

Table of Contents

Page

1. General Considerations S2

2. Procedures S3

A. General Procedures S3

B. Synthetic Procedures S5

3. Supplementary Figures S6

Figure S1. Polymerization kinetics of NBMe using catalyst 4 S6

Figure S2. Variable temperature 1H NMR of catalyst and DMAP S7

Figure S3. Variable temperature 31P NMR of catalyst and DMAP S8

Figure S4. Molecular weight of PNBMe with DMAP content S9

Figure S5. 1H NMR of soluble fraction of 20 wt% thermoset S10

Figure S6. TGA of PNBMe and thermosets S10

Figure S7. TGA of PNBMe made with varying solvents S11

Figure S8. DMA and DSC before and after temperature treatments S11

Figure S9. GPC before and after temperature treatments S12

Figure S10. 1H NMR before and after temperature treatments S12

4. NMR Spectra S13

5. References S18

Electronic Supplementary Material (ESI) for Polymer Chemistry.This journal is © The Royal Society of Chemistry 2016

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1. General Considerations

All chemicals were purchased from Sigma-Aldrich and used as received unless otherwise

specified. Solvents were purchased from Fisher Scientific and used without any further

purification. The chromium(III) salen catalyst was synthesized according to a previous report.1

Catalyst 4 (H2IMes{(H3C)2N-C5H4N}2Cl2Ru=CHPh) was synthesized according to literature

procedures.2

Nuclear Magnetic Resonance (NMR) spectra were recorded on a Varian U400, VXR500,

or U500 spectrometer using residual solvent peaks as reference. For 31P NMR, 85 % H3PO4 in a

glass capillary was used as an external reference. MestReNova (Version 8.1) software was used

to process all NMR spectra.

Gel Permeation Chromatography (GPC) was performed on a system equipped with an

isocratic pump (Model 1260, Agilent Technology) at a flow rate of 1 mL min-1 and a DAWN

HELEOS I MALLS detector (Wyatt Technology) and an Optilab rEX refractive index detector

(Wyatt Technology). The lasers for both detectors were set to 658 nm. Separations were

performed using serially connected size exclusion columns (102 Å, 103 Å, 104 Å, 105 Å, 106 Å

Phenogel columns, 5 µm, 300 × 7.8 mm, Phenomenex). The mobile phase consisted DMF +

0.1M LiBr. Samples were filtered through a 0.45 µm PTFE filter before analysis. The absolute

molecular weights and polydispersity of polymers were determined by using the dn/dc values

calculated in the Astra software (Wyatt Technology, Version 6.1.1).

Differential scanning calorimetry (DSC) was conducted on a TA Instruments Q20 with a

Liquid Nitrogen Cooling System. Tzero aluminum pans and lids were used to hold samples.

Scans were conducted under nitrogen at a flow rate of 50 mL/min. Samples were run under a

Heat/Cool/Heat program with heating and cooling rates set to 10 °C min-1 for Tg determination.

The second heating curve was used to calculate Tg using TA Universal Analysis software. For

cure exotherm, samples were quickly mixed, weighed, and placed into DSC pre-equilibrated at -

20°C. Samples were then heated at a rate of 10 °C min-1. Thermogravimetric analysis (TGA)

was conducted on a TA Instruments Q50 under nitrogen using alumina sample pans at a

heating rate of 10 °C min-1. Dynamic mechanical analysis (DMA) was conducted on a TA

Instruments Q800. Samples (l = 38 mm, w = 3 mm, t = 1 mm) were clamped into the instrument

and analyzed in tension mode. Samples were subject to an oscillatory strain of 1 Hz with an

amplitude of 15 µm. Heating was performed at a rate of 3 °C min-1 until a temperature of 175 °C

was achieved. All thermal data was processed using TA Universal Analysis (Version 4.5A).

Viscosities were measured on a DHR-3 combined motor/transducer rheometer from TA

Instruments with a 40 mm diameter and a 1.011 degree cone geometry. The temperature was

held at 25 °C using a Peltier plate system. The materials were loaded and trimmed and the

geometry was brought to the final gap of 30 μm. Controlled-velocity tests ramping up and down

the shear rate from 1 to 10 s-1 revealed no thixotropic or shear-thinning behavior. Final

measurements were performed at 3 s-1 for a duration of 60 seconds. The average viscosity

values were reported.

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2. Procedures

A. General Procedures

Polymerization Kinetics of NBMe

In a glass vial was placed 200 mg of NBMe. For polymerizations containing DMAP, 23 µl of a

10 mg mL-1 solution in CDCl3 was added. Then, CDCl3 was added, followed by 64 µl of a 25 mg

mL-1 solution of catalyst 1a to bring the total concentration of NBMe to 1.0 M. Samples which

required heating (55 °C) were placed in an aluminum heating block. At various times during the

reaction, 50 µl of solution was removed and placed into 650 µl of a 0.75 % (v/v) solution of ethyl

vinyl ether in CDCl3. Conversion was determined by comparing integrations of the olefin

protons appearing near δ 6.3 (monomer) and δ 5.5 (polymer).

Rate constants were determined by plotting ln([NBMe]) vs. time and dividing the resulting slope

by [1a] to yield second order rate constants. Due to the difficulty in determining the initiation

efficiency of 1a during the course of the reaction, rate constants assume the initiation to be

100 % complete and thus underestimate the value of the true rate constants.

Gel Time and Conversion of NBMe in Bulk

Polymerizations were conducted by adding desired amount of DMAP in DCM (50 mg mL-1) into

a vial and allowing to evaporate. NBMe (250 mg) was then added and stirred in the vial to

dissolve DMAP. Catalyst 1a was then added in xylenes (50 mg mL-1) and reaction allowed to

stand, inverting vials periodically to assess gelation (when inverted samples support their own

weight). Conversion of a separate batch of samples was assessed after heating samples to

100 °C for 1h, and allowing samples to sit overnight. Small samples were then cut from the

polymers and dissolved in CDCl3 for 1H NMR analysis.

Swelling of Polymers

Polymer samples with mass of ~ 250 mg were placed into 20 mL toluene and allowed to sit at

room temperature for 48 h. Samples were removed, gently dabbed with a Kimwipe to remove

excess solvent, and weighed. Swelling is defined as:

𝑆𝑤𝑒𝑙𝑙𝑖𝑛𝑔 (%) = 𝑀𝑓 − 𝑀0

𝑀0 𝑥 100

where Mf is the final mass of the swollen sample and M0 is the initial mass of the sample.

Gel Fraction

Polymer samples were placed in 20 mL chloroform and heated at 55 °C for 72 h, replacing the

solution with fresh chloroform every 24 h. Samples were then dried in a vacuum over for 72 h at

110 °C until constant mass. Gel fraction is defined as:

𝐺𝑒𝑙 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛 = 𝑀𝑓

𝑀0

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where Mf is the final mass of the dried sample and M0 is the initial mass.

ROMP Thermosetting Polymerization

Polyester crosslinker (NB-CL) and NBMe were mixed and heated with a heat gun to completely

dissolve polyester (once dissolved this formulation remains stable). After cooling to ambient

temperature, catalyst 1a (50 mg mL-1 in xylenes) was prepared by briefly sonicating and then

mixed with the resin for several minutes to ensure a homogenous solution. The resin was

poured into molds and cured by heating at 100 °C for 1 h.

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B. Synthetic Procedures

5-Norbornene-2,3-dicarboxylic acid dimethyl ester

The procedure was modified slightly from a previous report.3 In a 1L round bottom flask was

mixed endo-bicylco[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride (120 g, 731 mmol), methanol

(600 mL), and conc. sulfuric acid (1 mL). The regents were refluxed for 24 h. After cooling to

room temperature, 100 mL sat. NaHCO3 was added to quench the reaction, and the solvent

removed in vacuo to yield a cloudy paste. Water (200 mL) and sat. NaHCO3 (100 mL) was

added to the residue, which was extracted with 3 x 200 mL diethyl ether. The organic layers

were combined, washed with brine, dried over Na2SO4, and evaporated to yield a clear colorless

oil (131 g, 623 mmol, 85 % yield). 1H NMR (500 MHz, CDCl3): δ 6.26 (t, J = 1.2 Hz, 2H), 3.61 (s,

6H), 3.29 (m, 2H), 3.16 (s, 2H), 1.47 (dt, J = 8.7, 2.2 Hz, 1H), 1.32 (d, J = 9.0 Hz, 1H). 13C NMR

(100 MHz, CDCl3): δ 173.01, 134.96, 51.60, 48.75, 48.11, 46.32. HRMS (ESI) m/z calculated for

C11H15O4 [M+H]+: 211.0970, found 211.0980.

poly(endo-norbornene anhydride-alt-cyclohexene oxide)

The procedure was modified slightly from a previous report.4 In a 100 mL round bottom flask

was placed endo bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride (23.9 g, 146 mmol),

cyclohexene oxide (14.8 mL, 146 mmol), 4-dimethylaminopyridine (70 mg, 0.573 mmol), N,N’-

bis(3,5-di-tert-butylsalicylidene)-1,2-diaminobenzene chromium chloride (salph)CrCl1 (160 mg,

0.256 mmol), and toluene (38 mL). Reaction was purged with N2 for 15 min, then refluxed

under N2 overnight. Solution was diluted in an equal volume dichloromethane, and precipitated

into ~700 mL hexanes. Polymer was dried in a vacuum over at 100 °C for 48 h yielding 37.8 g

light orange powder (99 % yield). Mn = 8.0 kDa; PDI = 1.62. 1H NMR (500 MHz, CDCl3): δ 6.16

(m, 2H), 4.77 (m, 2H), 3.23 (m, 4H), 1.98 (s, 2H), 1.66 (s, 2H), 1.43 (s, 2H), 1.30 (s, 4H).

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3. Supplementary Figures

Fig. S1. Conversion of NBMe in CDCl3 initiated with 4 at various temperatures. [NBMe] = 1.0M,

[4] = 2.0 mM.

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Fig. S2. 1H NMR of catalyst 1a with (a) 1 equiv DMAP or (b) 2 equiv DMAP in toluene-d8 at

various temperatures. [1a] = 0.025 M. Molar ratios of catalyst species are given at 10 °C and

80°C. The upfield shift of the green resonance with increasing temperature suggests

dissociation of one DMAP ligand, shifting the equilibrium between 3 and 4 towards the

pentacoordinate ruthenium complex, 3.

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Fig. S3. 31P NMR of catalyst 1a with (a) 1 eq. and (b) 2 eq. DMAP in toluene-d8 at various

temperatures. [1a] = 0.025 M.

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Fig. S4. Molecular weight dependence of PNBMe when polymerized in bulk at 100 °C for 1h at

varying [NBMe]:[1a]:[DMAP] ratios. PDI values are typically < 1.1.

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Fig. S5. 1H NMR in CDCl3 of chloroform soluble fraction of 20 wt% NB-CL thermoset. Blue

indicates xylenes (83%) or ethylbenzene (6%), red indicates unreacted NBMe (3%), green

indicates NB-CL (4%), and purple refers to PNBMe (4%). Percentages refer to mol%.

Fig. S6. Thermal gravimetric analysis (TGA) of thermosets composed of NBMe containing

varying wt% of NB-CL.

NB-CL wt% Td (°C)a

0% 389

10% 389

20% 369

30% 355 a Onset point of degradation

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Fig. S7. TGA of PNBMe synthesized via bulk polymerization using a solution of 1a (50 mg

mL-1) in a variety of solvents to demonstrate 1st stage of weight loss is due to solvent loss.

[NBMe]:[1a] = 800:1.

Fig. S8. (a) Second heating DSC traces of PNBMe with a maximum temperature of 175 °C

(black) and 300 °C (red). Tg = 111 °C (black); Tg = 138 °C (red). (b) DMA of PNBMe on 1st

heating to 175 °C (black) then slowly cooling to 30 °C, and reheating sample to 175 °C again

(red).

Sample Td (°C)a Mass

Solvent (wt%)b

Xylenes 389 8.0

THF 387 8.2

DCM 386 11.8 a Onset point of degradation b Determined from 1H NMR

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Fig. S9. Normalized light scattering GPC traces from PNBMe samples before (black) and after

(red) DMA analysis.

Fig. S10. 1H NMR analysis of PNBMe samples before (black) and after (red) DMA analysis.

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1H NMR (500 MHz, d8-toluene, saturated solution): δ 19.55 (s, 1H), 8.46 (d, J = 4.9 Hz, 2H), 8.06 (d, J = 7.6 Hz, 2H), 8.02 (d, J = 6.7

Hz, 2H), 7.23 (t, J = 7.3 Hz, 1H), 6.99 (t, J = 7.8 Hz, 2H), 6.91 (br s, 2H), 6.63 (br s, 2H), 6.03 (d, J = 5.8 Hz, 2H), 5.44 (d, J = 6.9 Hz,

2H), 3.58 (d, J = 6.4 Hz, 2H), 3.46 (d, J = 7.4 Hz, 2H), 2.86 (br s, 6H), 2.41 (br s, 6H), 2.27 (s, 6H), 2.18 (br s, 6H),1.89 (s, 6H).

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